Enteropathogenic Escherichia coli Tir translocation and pedestal formation requires membrane cholesterol in the absence of bundle-forming pili
Enteropathogenic Escherichia coli Tir translocation and pedestal formation requires membrane cholesterol in the absence of bundle-forming pili
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DOI：
10.1111/j.1462-5822.2005.00654.x
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发表时间：
2006-04-01
影响因子：
3.4
通讯作者：
DeVinney, R
中科院分区：
文献类型：
--
作者：
Allen-Vercoe, E;Waddell, B;DeVinney, R
肠致病性大肠杆菌（EPEC）是全世界儿童腹泻的一个重要原因。毒力需要粘附在肠上皮细胞上，部分通过IV型束形成菌毛（BFP）和EPEC蛋白Tir介导。Tir被插入肠细胞质膜（PM），从而形成富含肌动蛋白的基座。Tir由III型分泌系统（TTSS）通过插入PM的EPEC蛋白组成的孔进行转运。在这里，我们证明在缺乏BFP的情况下，EPEC粘附，效应物易位和基座形成依赖于脂筏。使用甲基- β -环糊精（M β - CD）破坏脂质筏可将EPEC bbp缺陷菌株的粘附性从85%降低到1%。M β CD处理阻断了效应体Tir和EspF的易位，但仍形成了TTSS孔。在给予Tir后，M β CD处理使EPEC的基台形成从40%减少到5%，但相关病原体大肠杆菌O157:H7则没有，后者使用不同的Tir基机制。相反，表达BFP的EPEC可以规避对膜胆固醇的需求。这表明脂筏在这种医学上重要的病原体的毒力中起作用。
Enteropathogenic Escherichia coli (EPEC) is a significant cause of paediatric diarrhoea worldwide. Virulence requires adherence to intestinal epithelial cells, mediated in part through type IV bundle-forming pili (BFP), and the EPEC protein Tir. Tir is inserted into the enterocyte plasma membrane (PM), resulting in the formation of actin-rich pedestals. Tir is translocated by the type III secretion system (TTSS), through a pore comprised of EPEC proteins inserted into the PM. Here, we demonstrate that in the absence of BFP, EPEC adherence, effector translocation and pedestal formation are dependent on lipid rafts. Lipid raft disruption using methyl-beta-cyclodextrin (M beta CD) decreased adherence by an EPEC BFP-deficient strain from 85% to 1%. Translocation of the effectors Tir and EspF was blocked by M beta CD treatment, although the TTSS pore still formed. M beta CD treatment after Tir delivery decreased pedestal formation by EPEC from 40% to 5%, but not by the related pathogen E. coli O157:H7 which uses a different Tir-based mechanism. In contrast, EPEC expressing the BFP can circumvent the requirement for membrane cholesterol. This suggests that lipid rafts play a role in virulence of this medically important pathogen.